Stress relaxation of AA5182-O aluminum alloy sheet at warm temperature

摘要

Uniaxial tension and the subsequent stress relaxation tests at 25, 100, 200 and 300°C were conducted for AA5182-O aluminum alloy sheet with the thickness of 1mm in order to observe the temperature and strain rate dependency on its flow stress and stress relaxation. From the tension test results, it was observed that the stress-strain curves at 25 and 100°C were almost the same while the flow stress decreased with the increase of temperature. On the other hand, stress dropped at 100°C during relaxation even if almost no relaxation was found at 25°C. The degree of stress drop was pronounced more with the increase of temperature and the stress almost disappeared at 300°C. To reveal the relaxation mechanism, relaxation test followed by subsequent tension were performed at 100, 200 and 300°C. The re-yield stresses during subsequent tension at 100 and 200°C decreased compare to its flow stress at the end of pre-tension test (start of relaxation), while the stress did not changed at 300°C. The obtained results implies that the dominant mechanism of relaxation is grain boundary slide rather than dynamic recovery.